Common wave transmitter system



March 24 1942- R. HERZOG Erm.

` COMMON WAVE TRANSMITTER SYSTEM vFiled oct. 1s, 1939 s sheets-sneer 1 March 24, 1942. R. HERZOG ETAL 2,277,105

COMMON WAVE TRANSMITTER SYSTEM Filed OCT.. 13, 1939 3 Sheets-Sheet 2 m fr Seconda/w #ausm/'Mers l Alfa/nay Mardi 24 l942-. R HERZOG .fa-rm'. 2,277,105

'conos' 'mma TRANSMITTER sYsTau Patented Mar. 24, 1942 COMIMON `1f-AVE TRANSMITTER .SYSTEM Robert Herzog; Alfred Wissner; andErich- Schulze-Herringen, Berlin, and: Fritz: (lutz-t.- mann, Schneiche, -near BerlinyGermanmassignors toC. Lorenz Aktiengesellschaft, Berlin-v TempelhoLGermany, a company Application October 13, 1939,'SerialV No; 299,350 f In Germany October 13,- 1938i The present invention relates to frequency cone trol systems, and'more particularly to frequency control in common waver broadcasting'systems.

This invention has vfor anA object to providev a new method of and means for effecting commonk wave transmission in regions where it has been impossible in the past due tothe local-geographical conditions reliably to carry out such transmission. It is a well-known fact that the conditions of radio reception are extremely different in mountainous regions. This disadvantage may be overcome if a plurality of transmitters with a low output energy-is provided in the region to be covered with radio broadcasting signals.

Another object of this invention is to render economical theoperation of such a plurality of transmitters. This'problem` may 'be' solved by controlling the individual secondary transmitters with high frequency oscillations which are transmitted over cable or wirelines and by modulating these highfrequency signals `with low frequency oscillations, such as speech, music or other signals. The so modulated high frequency oscillations may directly, that is, without employing demodulating means, be used for controlling the frequency of the secondary transmitter of the common wave system.

Our invention will be more readily understood from the following description, taken in conjunction with the accompanying drawings, in

which Fig. 1 is a diagram showing one embodiment how to realize the idea of this invention, while the Figs. 2 and 3 each show a modification of the system as shown in Fig. 1.

Referring first to Fig. 1,` reference numeral I indicates a master transmitter, while II designates a secondary transmitter of a common wave system. The master transmitter I and the secondary transmitter II are connected with one an- 'i other over a conductive system, that is, open lines or cable lines. Special attention is called to the fact that the common wave transmitter system according to our invention is applicable also in the presence of open lines which have encountered considerable diculties in the common wave systems heretofore known in the art. This advantage is attained on account of the fact that the novel system operates with a low rate of frequency multiplication which renders the system 2. Modulation oscillations are impressed upon one vof the stages 2 througha cable line 4 and la The trans# j modulation frequency amplifiery 3.' mission lineinterconnecting the master trans-v mitter I and the secondary transmitter II is connected to the output of the master transmitter 2.'

This transmission line which comprises a number of open lline sections with intermediate repeaterlv stations 5 may be utilized in accordance with the principle of multiplex telephony or telegraphy over cable lines, that is, for simultaneously transmitting three different broadcasting performances without interfering the common wave'transmission system.

The' line connecting 1 the main transmitterv I with the secondary `transmitter II mayxbe used for carrier -wave multiplex wired radioitransmis'esion,forexample, for the simultaneous transmis-fA sion of' two or moreprograrnmesfv This will "not' interfere with'the common'wave controlling-sys#- 'tem. Fig. 1 shows howthis service may'beprov`l Y I5 `and I6 are carrier frequency trans-- vided( mitters which are connected to the line and which transmit programmes on carrier frequencies of 100 k. c. and 200 k. c. respectively. Repeaters 5 are designed to amplify the whole carrier frequency band from 100-200 k. c. I1 and I8 indicate subscribers stations connected to the line for receiving the modulated carrier waves, suitable known arrangements being provided at the substations whereby the subscribers are able to select either programme. A filter I9 provided in the input equipment of the secondary transmitter II allows only carrier waves of 150 k. c. and their side-bands to pass.

The modulated high frequency oscillations incoming at the secondary transmitter II are impressed upon a demodulator 6 and also applied to a frequency multiplier 9. The demodulator 6 separates the carrier frequency and the low frequency oscillations are conveyed to a modulator 1 which is adapted to modulate the secondary transmitter 8. The frequency mixture applied to and passing through the frequency multiplier 9 is impressed upon a phase-sensitive apparatus or phase bridge I i after amplication in an amplifier i0. It is assumed in the embodiment according to Fig. 1 that the device 9 effects a ten times carrier frequency multiplication as numerically indicated in this drawing by way of example. Also the transmitter 8 operates with a frequency which is ten times higher than the frequency incoming .to the secondary transmitter II. The frequency of the transmitter 8 is controlled by a quartz oscillator l2 through an amplier I3. The frequency of this quartz oscillator may be controlled by a frequency adjusting means I4 which substantially consists of a small condenser connected across the quartz crystal of the device I2. This condenser is subject to adjustment by mechanically unbiased movable means as disclosed in the copending U. S. application Serial No. 214,218, led June 17, 1938, granted January 28,

1941, as U. S. Patent No. 2,229,774 in the name of Erich Schulze-Herringen with assignment to C. Lorenz Aktiengesellschaft of Berlin (Germany). One portion of the frequency generated by the quartz oscillator I2 is branched ofl. from the amplifier I3 and applied to the phase-sensitive device II which in response to a phase departure actuates the frequency adjusting means I4. The operation of such phase sensitive means has been fully disclosed in the above-mentioned copending patent. In the present case, however, the output modulation frequencies will be morev or less distorted since the sidebands are likewise subjected to the multiplication. This condition has, however, no influence upon the operation of the present system because of the fact that the frequency'adjusting means I4 operates with mechanical damping, preferably oil damping means so that only modulations less than .5 cycle, which are not likely to be expected, may be able to exert any influence.

The system embodied in the Fig. 2 is a modification over that described in the foregoing. This figure shows a master transmitter in which a quartz controlled oscillator I generates a frequency which is higher, or alternatively lower than the frequency subject to transmission to the secondary transmitter. A frequency divider I5, or alternatively a frequency multiplier, is connected between the quartz controlled oscillator I' and the main transmitter 2. It is assumed by Way of example that the oscillator I generates a frequency which is ten times higher than the frequency to be transmitted to the secondary transmitter. The corresponding frequencies are indicated in this figure.

Fig. 3 shows an arrangement which permits a non-integer rate of the frequency radiated over the secondary transmitter to the frequency transmitted thereto from the master transmitter. Thisl arrangement which substantially corresponds to the secondary transmitter illustrated at II of Fig. 1, employs an additional frequency divider I6 connected in front of a frequency multiplier 9'. It is assumed in the present case that a frequency of kilocycles is incoming to this secondary transmitter. This frequency is divided by 5 so that a frequency of 30 kilocycles occurs at the output of the device I6. Now, this frequency becomes multiplied by 36 in the frequency multiplier 9 so that the frequency at the output side of this device is `equal to 1080 kilocycles. It is thus obvious with reference to the foregoing description in conjunction with Fig. 1 that a noninteger ratio of the incoming frequency and the radiated frequency of the secondary transmitter may be obtained. Such non-integer ratio may, of course, be directly accomplished in the frequency divider I6 in accordance with any known method.

What is claimed is:

The method of effecting common wave transmission, which comprises, generating a carrier frequency in a master transmitter, impressing low frequency modulation oscillations upon the carrier frequency in the master transmitter, transmitting the resulting low frequency modulated carrier frequencyA to a secondary transmitter over a line circuit, and causing the incoming modulated carrier frequency to effect frequency control in this secondary transmitter.

ROBERT HERZOG. v

ALFRED WIESSNER. ERICH SCHULZE-HERRINGEN. FRITZ GUTZMANN. 

